ABSTRACT
Free-range laying hen systems provide individuals a choice between indoor and outdoor areas where range use may be socially influenced. This study used radio-frequency identification technology to track the ranging of individually-tagged hens housed in six experimental free-range pens from 28 to 38 weeks of age (46â»50 hens/pen). All daily visits to the range were used to study group behaviour. Results showed that 67.6% (SD = 5.0%) of all hen movements through the pop-holes outdoors or indoors were following the movement of another hen ('pop-hole-following') compared to only 50.5% of movements in simulated random data. The percentage overlap in time that all combinations of hen pairs within each pen spent simultaneously outdoors or indoors showed a median value of overlap greater than the 90th percentile of random data. Pens housing hens that had been provided variable enrichments from 4 to 21 days (n = 3 pens) showed higher 'pop-hole-following' behaviour and a higher percentage of hen-pair association compared to hens reared in non-enriched conditions (n = 3 pens). These results show that birds in each free-range pen were primarily a cohesive flock and early enrichment improved this social cohesiveness. These results have implications for understanding free-range flock-level behaviour.
ABSTRACT
We investigated how individuality and lameness altered social organisation by assessing food-directed movement patterns in sheep. One hundred and ninety-six mature Merino ewes were walked in 16 different runs around a 1.1â¯km track following a food source. Flock position and lameness were measured and temperament was assessed using an Isolation Box Test. The mean value for the correlations of position between a run and the run preceding it was râ¯=â¯0.55⯱â¯SEM 0.03. All correlations between runs were positive (râ¯=â¯0.08-0.76) and all but two were statistically significant (Pâ¯<â¯0.05). The weakest and least statistically significant correlations were for run 14: where all 16 runs were conducted approximately 3 times a week, except with an interval of 20 weeks between runs 13 and 14. Additionally, there were differences in overall positions for a lame versus a non-lame individual (all Pâ¯<â¯0.05) with lame sheep being further back in position when compared to their non-lame mean positions. These results indicate the movement patterns, as measured by flock position during a food-directed forced movement order are relatively stable provided tests occur frequently, possibly on a bi-weekly basis. However, further work will be required to better account for individual animal variation.
